Bpas, which carries out a quarter of the abortions in the UK, said this was arcane and also called for nurses to be given powers to dispense the abortion pill, which can terminate a pregnancy up to nine weeks in.

One of the questions in the survey was should abortions be made legally available for everyone, 59% agreed with this, but the question did not spell out whether this required a change to the law or not.

Middle ground

The survey also showed that attitudes had shifted more towards the middle ground since 2001.

Fewer people taking part in the new poll had "very strong" opinions either supporting or opposing abortion than they did five years ago.

When those questioned were told of the rule requiring the consent of two doctors, more of them agreed with abortion within 24 weeks of pregnancy than when they were not given this information.

Ann Furedi, chief executive of the Bpas, said: "As at least one in three women in the UK can expect to have an abortion, it is not surprising that support for legal abortion remains quite strong, despite shrill campaigns by individuals who would like to see tighter laws.

"Abortion is a necessary back-up to birth control for couples who want to plan their families."

Marked difference

While a majority did back a woman's right to choose, different trends were revealed when individual circumstances were put to those questioned.

The poll showed a marked difference between men and women when it came to so-called "social abortions", in which the desire for a termination is not related to disability, or physical danger to the child or mother.

Some 44% of women approved, while 42% disapproved, compared to 51% of men approving and 34% disapproving.

The approval ratings were much higher if the circumstances invovled the baby having learning difficulties, physical disabilities and if the woman was under 16.

Ms Furedi suggested the finding was down to women's expectations of their ability to control their fertility and contraception.

"Women don't expect to get pregnant when they don't want to, and are more disapproving of women who do."

Psychological harm

Julia Millington, of the Prolife Alliance, said the survey took no account of the fact many believed there should be ways of reducing the number of abortions being carried out each year and the mounting "concern about the psychological and physical harm to women".

"While some women do find themselves in difficult situations and need proper help and support, the vast majority of abortions are not performed due to any grave or permanent health risk."

And Maggie Blott, of the Royal College of Obstetricians and Gynaecologists, said scrapping the two-doctor rule would be wrong.

"Some of the late abortions that are done are not straightforward so having the built-in safety net of two doctors is important, and you can't have one rule for them and another for women who have early abortions."

She also warned that while the abortion pill was extremely safe, complications could arise and it was important to have a doctor involved.

In 2005 there were 199,019 abortions in Britain, a 20% rise over ten years.

Bpas is the UK's largest provider of abortions, handling around 50,000 a year.